lkml.org 
[lkml]   [2006]   [Jan]   [15]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateSun, 15 Jan 2006 16:28:56 +1100
FromNick Piggin <>
SubjectRe: Race in new page migration code?
Christoph Lameter wrote:
> On Sat, 14 Jan 2006, Nick Piggin wrote:
> 
> 
>>>We take that reference count on the page:
>>
>>Yes, after you have dropped all your claims to pin this page
>>(ie. pte lock). You really can't take a refcount on a page that
> 
> 
> Oh. Now I see. I screwed that up by a fix I added.... We cannot drop the 
> ptl here. So back to the way it was before. Remove the draining from 
> isolate_lru_page and do it before scanning for pages so that we do not
> have to drop the ptl. 
> 

OK (either way is fine), but you should still drop the __isolate_lru_page
nonsense and revert it like my patch does.

> Also remove the WARN_ON since its now even possible that other actions of 
> the VM move the pages into the LRU lists while we scan for pages to
> migrate.
> 

Well, it has always been possible since vmscan started batching scans a
long time ago. Actually seeing as you only take a read lock on the semaphore
it is probably also possible to have a concurrent migrate operation cause
this as well.

Thanks,
Nick

-- 
SUSE Labs, Novell Inc.

Send instant messages to your online friends http://au.messenger.yahoo.com 

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-01-15 06:31    [from the cache]
©2003-2008